Pedantically speaking, offline card payments are already possible _now_. E.g. see the Square documentation about that.[1]

However, it requires that all the parties involved (issuer, acquirer, payment network, merchant) allow it, and there are certain limits. One of the linked documents[2] in the riksbank press release has more details about what they expect from these parties.

[1] https://squareup.com/help/us/en/article/7777-process-card-pa...

[2] https://www.riksbank.se/globalassets/media/nyheter--pressmed...